JavaFXLibrary can now be attached to process as java agent.

Building the docker demo failed because of missing package versions for
the newer Ubuntu image. Base image of the demo is now fixed to bionic
tag since Ubuntu updates have broken the build earlier as well.
Related Launchpad ticket:
https://bugs.launchpad.net/ubuntu/+source/openjfx/+bug/1799946

Experimental java agent support

Fix docker-compose up

…Screenshotdir, fixes #17

…, failure printout improvements

Screenshot and other fixes

…ion (#53)

looks good to me

* wrap runKeyword to asyncFx so that JavaFX operations are done FX thread

* more asyncfx fixes, went through whole code base

* new wrapping to asyncfx thread

* additional rewrite to have all needed kw's wrapped in FX thread, output and error handling improvements

* handle null object properlty, timeout to be generic kw timeout, handle separately wait until kws, kw output improvements

* fix hover related kw's

* waitUntilExists and waitUntilDoesNotExist improvements

* wait until keywords to have overall timeout value, improved printout

* fix text prefix to check for quotation marks

* fix text prefix to have support for apostrophe (') also

* cleanup

* fix verifiers hoverable kw's, add test

* fix push many times kw

* fix osx tests

* screenshots to asyncfx thread also in kw failure, fix hover kw's once more

* fix osx part and go throught documentation

* fix osx part and go throught documentation

* fix RunOnFailure to not store screenshot as mapObject to save memory

* remove comments